Performing Measurements in a Digital Cellular Wireless Telecommunication Network

1. A method for performing measurements in a digital cellular wireless telecommunication network, wherein the method comprises: determining free resources of a set of cells of the telecommunication network, wherein the set of cells comprises a plurality of mobile devices, and wherein the free resources are usable for exchanging data between base stations of the set of cells and the plurality of mobile devices; determining a subset of the plurality of mobile devices; setting the subset of the plurality of mobile devices into a probing mode; determining respective locations of the subset of the plurality of mobile devices in the probing mode; exchanging test signals between the mobile devices in the probing mode and the base stations of the set of cells, wherein the test signals comprise first and second pilot signals, wherein the first pilot signals are orthogonal to the second pilot signals, and wherein the test signals are exchanged by using the free resources; performing a plurality of measurements of signal strengths and/or signal powers of the test signals; determining average values from the plurality of measurements; and storing the average values of the plurality of measurements to provide a result of the measurement.

2. The method according to claim 1 , wherein the stored average values are used for predicting an effect of switching off at least one cell of the set of cells or switching the at least one cell of the set of cells from an operation mode into a sleep mode, wherein a base station of the at least one cell in the sleep mode consumes less energy than in the operation mode, wherein predicting the effect comprises: determining a first amount of resources needed in neighbouring cells of the at least one cell for serving the mobile devices of the at least one cell, if the at least one cell would be switched off or switched into the sleep mode, wherein determining the first amount of resources is performed by using the average values; determining a second amount of resources, wherein the second amount of resources comprises all free resources of the neighbouring cells; determining a coverage area of the at least one cell; and determining whether the neighbouring cells of the at least one cell would cover at least a part of the coverage area when the at least one cell is switched off by using the average values, wherein the at least a part of the coverage area is defined by mobile devices in the at least one cell having established a communication connection to the base station of the at least one cell; wherein the at least one cell is switched off or switched into the sleep mode if the second amount of resources comprises more resources than the first amount of resources and if the neighbouring cells cover the at least a part of the coverage area.

3. The method according to claim 1 , wherein the plurality of measurements are performed for subcarriers and time slots of the telecommunication network.

4. The method according to claim 1 , wherein the subset of the plurality of mobile devices is set into the probing mode by transmitting a request for setting each mobile device in the subset of the plurality of mobile devices into the probing mode to the subset of the plurality of mobile devices; determining if the probing mode is accepted by each mobile device in the subset of the plurality of mobile devices; transmitting an acknowledgement of the probing mode by these mobile devices that have determined to accept the probing mode; and setting these mobile devices that have transmitted the acknowledgement into the probing mode.

5. The method according to claim 4 , wherein each of the mobile devices in the subset determines if the probing mode is accepted by taking into account its respective battery load.

6. The method according to claim 1 , wherein the average values are stored in a central network entity, and wherein the central network entity performs a prediction of an effect of switching off at least one cell of the set of cells or switching the at least one cell of the set of cells from an operation mode into a sleep mode.

7. The method according to claim 6 , wherein the average values are stored together with the following information: measurement results of the plurality of measurements; cell identifiers of the set of cells; signal powers received at the base stations of the set of cells from the subset of the plurality of mobile devices; information about how many measurements have been performed for determining the average values, wherein the average values are not used for predicting the effect of switching off the at least one cell of the set of cells or switching the at least one cell of the set of cells from the operation mode into the sleep mode, if the number of measurements is below a reliability value for the respective locations of the subset of the plurality of mobile devices; traffic loads for each cell of the set of cells; and maximum traffic loads for each cell of the set of cells.

8. The method according to claim 1 , wherein the average values are stored in the base stations of the set of cells, and wherein these base stations of the set of cells perform a simulation of switching off at least one cell of the set of cells or switching the at least one cell of the set of cells from an operation mode into a sleep mode.

9. The method according to claim 1 , wherein determining the respective locations of the subset of the plurality of mobile devices in the probing mode is performed by using satellite navigation data and/or by positioning methods based on data of the telecommunication network.

10. The method according to claim 1 , wherein the set of cells is determined dynamically.

11. A central network entity for a digital cellular wireless telecommunication network, wherein the central network entity is configured to: communicate with base stations of a digital cellular wireless telecommunication network; determine free resources of a set of cells of the telecommunication network, wherein the set of cells comprises a plurality of mobile devices, and wherein the free resources are usable for exchanging data between base stations of the set of cells and the plurality of mobile devices; determine a subset of the plurality of mobile devices; control setting the subset of the plurality of mobile devices into a probing mode; determine respective locations of the subset of the plurality of mobile devices in the probing mode; control exchange of test signals between the mobile devices in the probing mode and the base stations of the set of cells, wherein the test signals comprise first and second pilot signals, wherein the first pilot signals are orthogonal to the second pilot signals, and wherein the test signals are exchanged by using the free resources; control performance of a plurality of measurements of signal strengths and/or signal powers of the test signals; determine average values of the plurality of measurements; store the average values of the plurality of measurements.

12. The central network entity according to claim 11 , wherein the central network entity is configured to perform a prediction of an effect of switching off at least one cell of the set of cells or switching the at least one cell of the set of cells from an operation mode into a sleep mode.

13. The central network entity according to claim 12 , wherein the central network entity is configured to store the following information: measurement results of the plurality of measurements; cell identifiers of the set of cells; signal powers received at the base stations of the set of cells from the subset of the plurality of mobile devices; information about how many measurements have been performed for determining the average values, wherein the average values are not used for predicting the effect of switching off the at least one cell of the set of cells or switching the at least one cell of the set of cells from the operation mode into the sleep mode, if the number of measurements is below a reliability value for the respective locations of the subset of the plurality of mobile devices; traffic loads for each cell of the set of cells; and maximum traffic loads for each cell of the set of cells.

14. A base station for a digital cellular wireless telecommunication network, wherein the base station is configured to: communicate with mobile devices of a digital cellular wireless telecommunication network; and communicate with other base stations of the telecommunication network; form a cell of the telecommunication network that belongs to a set of neighbouring cells formed by a corresponding set of neighbouring base stations; in cooperation with other neighbouring base stations, determine free resources of the set of neighbouring cells of the telecommunication network, wherein the set of neighbouring cells comprises a plurality of mobile devices, and wherein the free resources are usable for exchanging data between the neighbouring base stations of the set of neighbouring cells and the plurality of mobile devices; determine a subset of the plurality of mobile devices; set the subset of the plurality of mobile devices into a probing mode; determine respective locations of the subset of the plurality of mobile devices in the probing mode; receive test signals from the mobile devices in the probing mode, wherein the test signals comprise first and second pilot signals, wherein the first pilot signals are orthogonal to the second pilot signals, and wherein the test signals are received by using the free resources; perform a plurality of measurements of signal strengths and/or signal powers of the test signals; determine average values of the plurality of measurements; store the average values of the plurality of measurements.

15. The base station according to claim 14 , wherein the base station is configured to use the stored average values for predicting an effect of switching off at least one cell of the set of neighbouring cells or switching the at least one cell of the set of neighbouring cells from an operation mode into a sleep mode; wherein the base station, in cooperation with the other neighbouring base stations, is configured to determine a first amount of resources needed in the set of neighbouring cells for serving the mobile devices of the at least one cell, if the at least one cell would be switched off or switched into the sleep mode, wherein determining the first amount of resources is performed by using the average values; wherein the base station, in cooperation with the other neighbouring base stations, is configured to determine a second amount of resources, wherein the second amount of resources comprises all free resources of the set of neighbouring cells; wherein the base station, in cooperation with the other neighbouring base stations, is configured to determine a coverage area of the at least one cell; wherein the base station, in cooperation with the other neighbouring base stations, is configured to determine whether the set of neighbouring cells of the at least one cell would cover at least a part of the coverage area when the at least one cell is switched off by using the average values, wherein the at least a part of the coverage area is defined by mobile devices in the at least one cell having established a communication connection to the base station of the at least one cell; wherein the base station, in cooperation with the other neighbouring base stations, is configured to switch the at least one cell off or into the sleep mode if the second amount of resources comprises more resources than the first amount of resources and if the neighbouring cells cover the at least a part of the coverage area.

16. The base station according to claim 14 , wherein the base station is configured to set the subset of the plurality of mobile devices into the probing mode by: transmitting a request for setting each mobile device in the subset of the plurality of mobile devices into the probing mode to the subset of the plurality of mobile devices; determining if the probing mode is accepted by each mobile device in the subset of the plurality of mobile devices; receiving an acknowledgement of the probing mode by these mobile devices that have determined to accept the probing mode; and setting these mobile devices that have transmitted the acknowledgement into the probing mode.

17. The base according to claim 14 , wherein the base station, in cooperation with the other neighbouring base stations, is configured to perform a simulation of switching off at least one cell of the set of neighbouring cells or switching the at least one cell of the set of neighbouring cells from an operation mode into a sleep mode.

18. A mobile device for use in a digital cellular wireless telecommunication network, wherein the mobile device is configured to: at least a transmitter configured to communicate with base stations of a digital cellular wireless telecommunication network; wherein, when the telecommunication network is operating to serve a load for a set of cells formed by a corresponding set of base stations, there are used resources of the set of cells serving the load and free resources of the set of cells known by the telecommunication network to be free, wherein the set of cells comprises the mobile device and other mobile devices, wherein the free resources are usable for exchanging data between the base stations of the set of cells and the mobile device; wherein the mobile device is configured to set itself into a probing mode; wherein the mobile device is configured to determine its location within the set of cells; wherein, in the probing mode, the mobile device is configured to receive test signals broadcast by the base stations of the set of cells, wherein the test signals comprise first and second pilot signals, wherein the first pilot signals are orthogonal to the second pilot signals, and wherein the test signals are received by using the free resources; wherein, in the probing mode, the mobile device is configured to perform a plurality of measurements of signal strengths and/or signal powers of the test signals; wherein, in the probing mode, the mobile device is configured to send the plurality of measurements and a reliability indicator to the base stations of the set of cells.

19. The mobile device according to claim 18 , wherein the mobile device is configured to receive a request signal broadcast by the base stations of the set of cells requesting the mobile device to enter the probing mode; wherein the mobile device is configured to check device parameters to decide whether to accept or deny the probing mode request; wherein, after deciding to accept the probing mode request, the mobile device is configured to set itself into the probing mode and determine its location; wherein, after deciding to accept the probing mode request, the mobile device is configured to send a feedback signal indicating acceptance to at least one base station of the base stations of the set of cells.

20. The mobile device according to claim 18 , wherein the mobile device is configured to determine if the probing mode is accepted by taking into account a battery load for the mobile device.

21. The mobile device according to claim 18 , wherein the mobile device is configured to determine its location using satellite navigation data and/or by positioning methods based on data of the telecommunication network.

22. The mobile device according to claim 18 , wherein, in the probing mode, the mobile device is configured to broadcast uplink test signals for reception by base stations of the set of cells.